ENTOMOLOGICAL INVESTIGATIONS OF AN OUTBREAK OF JAPANESE ENCEPHALITIS IN THREE DISTRICTS OF CHHATTISGARH, INDIA IN THE YEAR 2017

1. Shankarlal Agrwal Science College Salekasa, RTM University Nagpur 441916, India. 2. Tai Golwalkar Mahavidhyalaya, Ramtek, RTM University Nagpu 4 441106, India. 3. CME&VM, NCDC, Delhi 110054, India. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 05 December 2019 Final Accepted: 07 January 2020 Published: February 2020


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preference are similar in all the major genotypes of JE virus. The first isolation of JEV in the Republic of Korea (ROK) was made during an autopsy of an American soldier at Incheon in 1946 (Sabin et al. 1947). JE, has emerged as a major public health problem in India since 1955 from Vellore, north Arcot district with a very high mortality and morbidity (Work and Shah 1956). It is most prevalent in rural and peri-urban areas. It is the main cause of viral encephalitis in many countries of Asia spreading over three million populations (Ghosh and Basu 2009).The first JEV was isolated based on serological surveys in 1955, in Tamil Nadu, India (Namachivayam and Umayal 1982).It is one of the major encephalitis in the tropical regions of Asia, including India, China, Japan, Taiwan, Korea and Philippines (Solomon 1997). In India Since 1955, many major outbreaks have been occurred in different parts of the country including Andhra Pradesh, Assam, Bihar, Goa, Karnataka, Manipur, Tamil Nadu, Uttar Pradesh and West Bengal. Outbreaks of JE usually coincide with monsoons and post-monsoon period when the vector density is high (Sudhanshu et. al. 2018).
The JE case-fatality rate varies across ranging from 10 to 30% among infected patients (Libraty et al. 2008). Among those with disease symptoms; 20-30% of those who survive suffer permanent neuropsychiatric sequelae Most of the cases having very little or no symptoms of the disease, sometimes inflammation of the brain occurs. Symptoms may be included meningism, like neck rigidity, photophobia, nausea, headache, vomiting, fever, confusion, and seizures and altered sensorium. Abnormal movements like coarse tremors, convolutions are seen in children. Neurological sign develops like ataxia, abnormal reflexes, paralysis, delirium, prolonged confusion with poor prognosis. Incubation period of the JEV may be 5 to 15 days after infection. There are paralysis and mental retardation in 30-70 percent survivors. In areas where the JE virus is common, encephalitis occurs mainly in young children because older children and adults have already been infected and are immune. Japanese encephalitis virus (JEV) is transmitted through mosquito and maintained in a zoonotic cycle, which can be both enzootic and epizootic. JE has been isolated from 16 species of mosquitoes belonging to the genera of Culex (10), Anopheles (3) and Mansonia (3) (Philip Samuel et al. 2000). The Culex vishnui subgroup of mosquitoes consisting of Cx. tritaeniorhynchus, Cx. vishnui and Cx. pseudovishnui have been implicated as major vectors of JE in different parts of India (NVBDCP 2018). Human is the accidental host (Fig.2). Human is also the dead-end host. Pigs are the major reservoir/amplifying host for JE virus and water birds such as Heronetc.are the carriers for JEV. There is no human to human transmission reported till date. Environmental factors such as temperature rain fall humidity etc., plays an important role in transmission of JE virus in population. JE Virus transmission is seasonal in temperate areas of Asia, Human disease usually peaks in the summer and fall. Transmission pattern in the subtropics and tropics, can occur year-round, often with a peak during the rainy season. Several factors like temperature pattern, distribution of vector population, agriculture practices (wetland rice crop) swine rearing and their proximity to human populations are responsible for JE outbreaks in India (Lin & Lu 1995, Gingrich et al.1992 Specific treatment for Japanese encephalitis is not available and treatment can be supportive with assistance given for feeding, breathing or seizure control as required. Raised intracranial pressure may be managed with mannitol. Japanese encephalitis (JE) vaccine is the only JE vaccine is available. JE vaccine is recommended for long time travelers who are plan to visit for long time (More than One month) in endemic areas during the JE virus transmission season. Pregnant women are on high risk who must travel to an area where risk for infection is high should be vaccinated with when the risk of immunization is significant than by the risk of infection . Prevention is always safe and effective with the Japanese encephalitis vaccine. Other measures including avoidmosquito bites with the use of personal protection measures as mosquito repellent, use of bed net etc, (WHO 2015). JE vector species of mosquitoes are known to be zoophilic, and mostly preferring cattle for feeding over man (Carey et al 1969). In India a large number of Cattle-pig ratio is predominant. JE vectors are primarily zoophilic and exophilic in nature, however due to their high density, particularly during outbreaks/ epidemicsman-vector contact may reach at significant level even indoors.
Three districts of Chhattisgarh are recently affected with an outbreak of JE disease with a total of 13 cases and 2 deaths. Outbreak started from 28.11.2017 from Dondapal block of Sukma district. it spreads in 3 nearby districts namely Dantewada, Bastar and Bijapur. All the affected patients age ranges from 1-5 years' age group. Females were more affected than males. In some patients mixed infection was also reported. Some patients were affected with Dengue, Malaria & Japanese encephalitis (JE). One patient was died of mixed infection of Dengue, Malaria & JE. All the patients tested with IgM E Elisa in Jagdalpur Hospital. In view of the severe outbreaks with life losses and on the request of the Health department, Govt. of Chhattisgarh, an entomological investigation was carried out in all the affected villages during the outbreak period to assess the prevalence of JE vectors, their infection status, risk factors for transmission of JE and to suggest appropriate vector control intervention measures for 163 implementation by the state/district Health Department. A team from NCDC, Delhi visited in the JE affected areas for a period of 20 th December 2017 to 1 st January 2018 and an entomological survey was carried out to identify the vectors involved in the transmission of this disease. Survey was carried out in all the Japanese encephalitis affected villages.

Materials And Methods:-Study area:
Chhattisgarh is located in the center-east of the country. It is the tenth-largest state in India,it covers an area of 135,191 km 2 ,with 25.5 million population (Census 2011). About 44% of the total area of Chhattisgarh is covered by forest. The climate of the state is mainly dry and hot. Chhattisgarh receives a good amount of rainfall. The state receives rainfall mainly from the South West monsoon. Temperatures in Summer Chhattisgarh can reach 45 °C. The rainy season is from June to October but in winter it is very in morning and evening. Chhattisgarh receives an average of 1,292 millimeters (50.  (87) and Sukma (46). These all three districts surrounded by forest. Chhattisgarh is a basically tribal state with majority of population residing in rural areas. Chhattisgarh is boarded by Madhya Pradesh on its north western part, Maharashtra on the west and Andhra Pradesh on its south. Main crop of these district is paddy.

Epidemiological Data collection:
Epidemiological investigations included discussion with the District authorities and to know the background information of the affected areas, genesis of outbreak, investigations carried out so far and control measures undertaken; visit to affected areas. Data for the last 3 years of VBD's of all four districts was obtained to assess the current situation of outbreak from District authorities. Besides this Descriptive analysis on the basis of time, place and person was carried out. Collected data was analyzed and plane of investigation made accordingly.

Entomological investigations:
Entomological investigation was carried out as per the guidelines of NVBDCP, Delhi. Various entomological parameters were observed during outbreak investigation. Following parameters were used: Ecological Condition: Ecological condition of the JE affected areas was assessed to check whether pigsty is near to human dwellings or not, present of water birds like Water Herons, Egret bird etc. Presence of water bodies in which vector species of mosquito can breed.

Mosquito collection: Adult Collection:
Adult mosquito collection was done normally early in the morning 7.00-9.00 AM, with the help of Torch and aspirator to know the vector density from both human dwellings and cattle shed. This method is also used to know the indoor resting density. Per Man Hour density was calculated with the help of following formula:   (4) and Sukuma (2) with nil death. The epidemiological trend of VBD's in all these four districts are given in Table 1.  Mosquitoes collected from Dantewada in Outdoor collection (Fig.2.) shows that only two species of culex and 10 species of anopheles were collected. PMHD for Cx. quinquefasciatus was 16 170 indoors and outdoors with 5% malathion and 5% cyphenothrin, larvicidal (Bti) spray in temporary breeding habitats found inside the villages has been started and LLINs/non-impregnated nets were also distributed in the affected villages. Pigs are the reservoir host for JE virus, In most of visited villages pigsties were found near human dwellings so it was suggested to community to keep the pigs in pig pens constructed in the isolated places 2.5 km away from the villages. Community awareness programme of health education and social mobilisation has been started by state health authority in all the JE affected areas.

Conclusion:-
JEV is emerging as a serious threat to human in most of the country first case was reported in the year 2017 in these affected areas of Chhattisgarh.The study has identified the potential or actual larval habitats of mosquitoes and adult vector density of Japense encephalitis in all the affected areas. As Pigs are the reservoir host of JEV, Pigisties are are observed in all the affected ares near the human dwelling. The abundance of JE vector and incidence of JEV cases in both rural and urban areas necessitate intensified surveillance and control of mosquito during high temperature and rainfall seasons. Culex tritaeniorhynchus, the main vector of JE was collected during hand collection both from human dwelling in Babusemra village, Avantika Colony, Binta and Salemeta villages of district Bastar.hich may act as an effective strategy for controlling the burden of JE fever. Fogging was done in some areas. No regular anti larval operations were carried out in all the affected areas. Lack of IEC was observed in the affected community about vector borne disease.

Recommendation:-
Regular anti larval operations are required in all these affected areas. Paddy fields are potential breeding place throughout the year so regular anti larval measures should be ensured there. Piggeries may be kept away from human dwellings. Regular entomological surveillance should be carried out in affected areas as well as in adjacent areas to determine vector density for proper control measures. Reorientation training of field staff is needed and should be done on priority basis. IRS may be carried out in piggeries on regular interval. LLIN may be distribute in all affected areas to reduce man mosquito contact.